A subscriber identification module (SIM) card containing subscriber identification information is typically used in an electronic device such as a mobile phone or the like. In addition, a secure digital (SD) card or the like is used in such an electronic device as a memory card for storing data. Such an SD card or a SIM card is typically loaded onto a card tray, and the SD card or the SIM card loaded onto the card tray may be electrically connected to the electronic device by inserting the card tray into a card socket.
As electronic devices become miniaturized in recent years, a card tray capable of loading a plurality of electronic cards is suggested in the related art, and a card tray having an SD card and a SIM card loaded thereonto in a stacking manner is suggested as an example thereof.
However, in the related-art card tray onto which the SD card and the SIM card are loaded in the stacking manner, when the SD card and the SIM card are loaded onto the card tray to have a terminal unit of the SD card and a terminal unit of the SIM card face in the same direction, the card socket into which such a card tray is inserted should have a contact terminal for being brought into contact with the terminal unit of the SD card and a contact terminal for being brought into contact with the terminal unit of the SIM card disposed on the same plane of the card socket (for example, a lower surface of the card socket) without overlapping each other. To this end, it is difficult to make the area of the lower surface of the card socket small and thus it is difficult to miniaturize the card socket.
In addition, in the related-art card tray onto which the SD card and the SIM card are loaded in the stacking manner, when the SD card and the SIM card are loaded onto the card tray to have the terminal unit of the SD card and the terminal unit of the SIM card face in different directions, the card socket into which such a card tray is inserted should have a contact terminal for being brought into contact with the terminal unit of the SD card and a contact terminal for being brought into contact with the terminal unit of the SIM card disposed on opposite planes of the card socket (for example, an upper surface and a lower surface of the card socket), respectively. To this end, it is difficult to make the thickness of the card socket small and thus there is a limit to miniaturizing the card socket.
Meanwhile, Japanese Laid-Open Patent Publication No. 2015-109182 suggests a card socket employing a card tray having an SD card and a SIM card loaded thereonto in a stacking manner. The card socket suggested in the above-mentioned document includes an upper shell, an upper housing provided with an upper contact terminal, a lower housing provided with a lower contact terminal, and a lower shell. When such a card socket is manufactured, the upper housing and the lower housing are assembled with each other and the upper shell and the lower shell are assembled with the upper housing and the lower housing, respectively. However, the upper housing and the lower housing are manufactured by nonconductive synthetic resin having relatively low strength. Therefore, when the card tray is abnormally inserted into the card socket and is brought into contact with the upper housing or lower housing of the card socket, the upper housing and the lower housing assembled with each other may be disassembled from each other or the upper housing or the lower housing may be deformed by the force pushing the card tray into the card socket. That is, the card socket may be unexpectedly damaged due to wrong insertion of the card tray and thus it is difficult to guarantee stable performance of the card socket.
Patent Document 1: Japanese Laid-Open Patent Publication No. 2015-109182